Thermostat



July 22, 1930. G. A.ROBERTSHAW I 1,771,316

THERMOSTAT Filed Septv 30, 1927 INVENTOR Patented July 22, 1930 PATENT OFFICE GEORGE A. ROBERTSHAW, OF GREENSBURG, PENNSYLVAIIIA THERMOSTAT Application filed September 30, 192?. Serial No. 223,025.

This invention relates to thermostats, and more particularly to a thermostat having means for setting or resetting the same.

In thermostats of the type which are commonly'used with various appliances, such, for instance, as domestic cooking stoves, ovens and the like, there is usually providedan adjustable dial or indicator and a graduated surface for cooperation. The thermostat must be properly set with reference to the calibrations of the indicator. The present invention has for its object to provide a novel construction by'means of which the setting or resetting of the thermostat may be easily and properly effected and whereby such adjusting mechanism cannot be easily tampered with.

.The invention may be'readily understood by reference to the accompanying drawings which illustrate certain embodiments of my invention and in which Figure 1 is a side elevation of a thermostat having a regulating indicator and having resetting mechanism embodying the present invention, part of the structure being shown in section; Figure 2 is a front elevation of the cali- -.brated valve disk,"

Figure 3 is a side elevation of this valve disk, together with the bearing cap thereon, part of the structure being broken away and indicated in section to show the locking screw; and 1 Figures 4 and 5 are views corresponding to 35 Figures 2 and 3 respectively, of a slightly Jnodified arrangement.

In the drawings, I have illustrated the invention as being applied to a thermostat of the type shown in Robertshaw Patent No. 1,455,663 dated May 15,1923, but it will be understood that the invention is applicable to other forms of thermostats.

In the drawings, 2 designates an expansihle sleeve having a rod 3 therein, whose coefi1 cient of expansion is relatively low. At the forward end of the sleeve 2 is a casing2 In the casing 2 is a valve disk 4, adapted to seat on an annular flange 5 inside the casing and which is adapted to control the flow of gas port 7. The disk 4 is-urged closed by a spring 8 bearing against it, this spring bemg confined by a removable cap 9. 7

At the center of the disk 4 is a threadedhub 10 on to which is screwed a cap 11. Passing through the disk 4 is a set screw 12 adapted to bear against the cap 11 to normally look it against rotation on the hub. Passing through the boss and bearing against the inside of the capll is an extension 13 of the 6 inner rod 3 of the thermostat.

The exterior of the casing 2 is calibrated. Adjustably secured to the sleeve 2 is a control handle 14 having an indicator 15 adapted to cooperate with the calibrations on the exterior of the casing 2 The general operation of the thermostat is the same as outlined in the said patent dated May 15, 1923. By moving the handle 14, the temperature at which the valve closes can be changed, and the temperature at which the valve will close will be indicated by the pointer 15. In order to provide for the proper setting of the pointing 15 with reference to the calibrations on the outside of the valve 2, the adjustable cap 11 is provided, By turning the cap 11 in one direction the point of contact for the pin 13 with reference to the valve disk is either moved in or out so that the operation of the thermostat is correspondingly changed. The valve disk 4 is therefore calibrated. In Figure 2, I have shown the disk calibrated into sections representing 25 of temperature. The cap 11 is provided with an arrow or other suitable indicating marking. In the original assembly of the thermostat, this arrow points to the first marking on the disk, as shown in Figure 2. If upon subsequent test it develops that the actual temperature at which-the thermostat operates is too low with reference to the temperature indicated by the pointer 15, the cap 11 is screwed in a clockwise direction with reference to Figure 2. If, for instance, the discrepancy is 75; the cap is turned through 5 3 graduations on the disk. If, on the other hand, the discrepancy between the two is in the opposite relation, the cap 11 is screwed in a counterclockwise direction. It will be between the inlet connection 6 and the outlet understood that the cap 11 can be turned to ations being set at 25 merely for the purpose of convenience.

In order to set the thermostat, the cap 9 is removed, after which the valve disk can be lifted off the pin 13 and the set screw 12 loosened. The cap 11 can then be adjusted to the necessary extent and the set screw 12 tightened and the parts replaced. It will be understood that this adjustment is entirely independent of such adjustment as may be obtained by varying the connection between the operating handle 14: and the sleeve 2. This adjustment may be efiected by means of a set screw 16, but frequently the set screw 16 is not readily accessible and access thereto cannot be easily had without removing the thermostat altogether from the structure in which it is mounted. The adjustment thus provided on the valve disk itself is alsoof advantage in checking the thermostat by what is known as the cold checking and cold setting means. In checking and setting the ther stat according to this method, the user termines whether the thermostat ..is set correctly without lighting up the oven or checking it against actual temperature. To do this the operator would set the pointer 15 at a given designation on the casing 2 say 250, then he would determine the room temperature, which, for instance, may be assumed as? 0. He would then remove the valve cap 9,take out the valve disk 4, move the adjusting cap 11 counterclockwise for a distance of 250 less or-lSO. He would then tighten the set screw 12, replace the parts, turn on the gas, and if the gas to the burner were shut off or nearly shut off, he could be sure of the'thermostat being set sufficiently close for practical purposes. By making additional tests above or below room temperature, a very accurate determination could be made and a very accurate setting of the thermostat could be secured.

. The arrangement shown in Figures 4 and 5 is generally similar to that described in connection with Figures 1 to 3, inclusive, but instead of the nut or cap 11 belng threaded on to the exterior of the hub of the valve disk, designated 17-, the hub is interionly threaded at 18 and the nut 19 is screwed into the interiorly threaded hub 18. Confined between the nut 19 and the valve disk, is a compression spring 20 which serves to hold templation of my invention, and under the scope of the following claims.

I claim:

1. In a thermostat, a casing, an ex ansible member, an adjustable connection etween the expansible member and the casing, an operating handle for eflecting the adjustment, calibrations on the casing with which the handle cooperates, a non-expansible member, a valve inside the casing, and a calibrated adjustable connection betweenthe valve and the non-expansible member.

2. In a thermostat, a casing, a removable cover for the casing, an expansible member connected'with the casing, a non-expansible member inside the expansible member ha ing an inner terminal projecting into. e casing, a valve disk on the inner terminal cooperating with a valveseat in the casing, and a threaded connection between the valve disk and the terminal for adjustably varying the effective position of the valve on the terminal, said valve having calibrationsthereon coordinated with the threaded connection.

3. A valve comprising a body, a valve seat therein and a valve disk cooperating therewith, an actuating member for said disk and.

calibrated adjustin means for varying the relation of said dis and member, auxiliary ad ust ng means having threaded engagement with said disk whereby said disk may;

be moved axially of said actuating member, and cooperating index and graduati ns on sa1d disk and auxiliary adjustingmeans.

4. A valve comprising a body, a valve seat} therein and a valve disk cooperating therewith, means for actuatin the disk, adjusting means for the disk, 9. oss thereon, a cap threaded on said boss and engaging said actuating means, whereby. the adjusted setting of said valve may be corrected and index and calibration marks on said cap and disk.

In testimony whereof I have hereunto set my hand.

GEORGE A. ROBERTSHAW.

the nut against independent rotation and thereby eliminates the necessity for the set screw 12'shown in Figure 1. The general operation and arrangement is otherwise similar to the construction shown in Figure 1.

Various other changes and modifications may be made in the particular construction and arrangement of the parts within the con- 

